For many years, wheelchairs have provided an adequate vehicle for meeting the short-term transportation requirements of the ill, handicapped, elderly or otherwise infirm. While improvements have been made with respect to various aspects of the wheelchair, there still remain some areas that are susceptible of improvements.
By way of example, during the manufacture and assembly of wheelchairs, different diameter casters are often employed on different wheelchairs to effect a particular result. In some instances, it may be useful to mount larger diameter casters on the wheelchair while in other instances, the use of smaller diameter casters may prove to be more beneficial. Moreover, to increase the performance of the wheelchair by reducing the flutter of the caster, the caster is preferably mounted in such a way that the axle of the caster is set back rearwardly from the longitudinal axis of the mounting stem. Typically, the larger the diameter of the caster, the greater the amount of trail that is necessary to inhibit flutter. However, the amount of trail imparted to the caster must be weighed against the fact that the larger the setback of the caster, the more likely the caster will come into contact with the individual's foot during turning movement of the wheelchair. In typical wheelchair designs, changing the diameter and/or the trail of a caster requires removal and replacement of the entire caster mounting assembly.
Another area in which known wheelchairs are susceptible of improvements concerns the foot rest mounting assembly to which is attached to the foot plates for supporting an individual's feet. Usually, the foot plate is mounted on a frame member that extends downwardly and somewhat forwardly (i.e., not vertical). If the foot plate is attached to the end of the frame member such that the plane of the foot plate is perpendicular to the longitudinal axis of the frame member, the foot plate would be positioned at an undesirable angle, thereby providing discomfort to the individual. Thus, as seen in FIG. 9, some wheelchairs are designed such that the distal end 50 of the frame member 52 is bent downwardly slightly to result in a generally vertically oriented end. In that way, the foot plate 54 is oriented in a more horizontal manner so that the individual's foot assumes a more natural position when supported on the foot plate 54. Unfortunately, bending the distal end 50 of the 52 in the manner illustrated in FIG. 9 increases manufacturing costs and is somewhat more time consuming than would otherwise be the case if bending was not required.
An additional area of improvement for wheelchairs concerns the disposition of the foot plate frame member on the wheelchair frame assembly. Typically, because the hips of an individual are normally the widest part of the individual's body, the side frame assemblies defining the wheelchair frame must be spaced apart a sufficient distance to accommodate the individual's hips. However, the dimension across the portion of an individual's legs located below the hips typically decreases in the direction of the feet. With that in mind, other known wheelchairs attempt to provide some amount of lateral support for the legs by configuring the foot rest frame members 60 in the manner illustrated in FIG. 14. In particular, the foot rest frame members 60 are provided with an inwardly bent portion so that the lower portions of the frame members 60 are spaced apart by a distance less than the distance between the side flames 62. However, such a construction of the frame members 60 increases the manufacturing costs due to the fact that the frame member 60 must be bent during fabrication. Further, the frame members 60 illustrated in FIG. 14 do not take into account the fact that the width of an individual's body along the length of their legs gradually decreases from the hips to the feet. Thus, while the inwardly bent portions of the frame members 60 may provide some amount of lateral in the knee region of the legs, they provide little support for the portion of the legs located below the knee.
A still further area in which known wheelchairs are susceptible of improvements involves the way in which the adjustment of some characteristics of the wheelchair affects other characteristics of the wheelchair. For example, in some known wheelchairs, adjustment of the seat angle adversely impacts upon the caster alignment. Also, seat pan angle adjustment can cause the drive wheels to tow, thereby adversely impacting the wheelchair's performance. Further, attempts to increase or decrease the wheel base through forward or rearward movement of the drive wheels can affect the seat pan angle.
From a manufacturing and assembly standpoint, many known type of wheelchairs provide little flexibility in designing the wheelchair to meet the needs and the performance characteristics of various individuals. That is, manufacturing and assembling a general purpose wheelchair, for example, requires one complete set of component parts, while the fabrication of a more high performance wheelchair requires a completely different set of component parts. Thus, the manufacture and assembly costs associated with those known types of wheelchairs may be unnecessarily high.